Long-wavelength infrared zoom system using tunable concave and convex mirrors

Abstract

We propose and demonstrate a long-wavelength infrared (LWIR) zoom system with focus tunable mirrors. The designed system consists of two focus tunable mirrors, four static lenses, and a detector. The zoom magnification can be changed by altering the focal length of the two mirrors through a control of the radius of the surface curvature of the mirrors. The shape of the mirrors can be concave or convex, which means that the focal length can vary from negative to positive. The fixed-focus lenses are designed to correct the aberrations of the tunable mirrors and are made of a material with good transparency at LWIR. Following the above design, an LWIR zoom system with the characteristic of being concave or convex is realized for the first time, and its results demonstrate 2x magnification and speeds up to 5 Hz. The proposed zoom system is free from mechanical moving parts and has potential as a low-cost LWIR system with high-speed zoom.